Volcanic Eruption

Definition

A type of volcanic event near an opening/vent in the Earth’s surface including volcanic eruptions of lava, ash, hot vapour, gas, and pyroclastic material (IRDR Glossary).

The majority of volcanoes in the world form along the boundaries of Earth's tectonic plates. When tectonic plates collide, one often plunges deep below the other in what's known as a subduction zone. Not all volcanoes are related to subduction: another way volcanoes can form is what's known as hotspot volcanism. In this situation, a zone of magmatic activity—or a hotspot—in the middle of a tectonic plate can push up through the crust to form a volcano. Although the hotspot itself is thought to be largely stationary, the tectonic plates continue their slow march, building a line of volcanoes or islands on the surface (National Geographic).

A volcano is currently active if it is erupting lava, releasing gas or generating seismic activity. An active volcano is labelled dormant if it has not erupted for a long time but could erupt again in the future. When a volcano has been dormant for more than 10 000 years, it is considered extinct. Volcanoes can remain inactive, or dormant, for hundreds or thousands of years before erupting again. During this time, they can become covered by vegetation, making them difficult to identify.

How explosive a volcanic eruption is depends on how easily magma can flow or trap gas. If magma is able to trap a large amount of gas, it can produce explosive eruptions. (Australian Government).

Facts and figures

Over the last 11,500 years, more than 1,500 major eruptions have occurred, with approximately 500 in the Pacific "Ring of Fire" alone (PreventionWeb).

There are volcanoes on every continent, even Antarctica. Some 1,500 volcanoes are still considered potentially active around the world today; 161 of those—over 10 percent—sit within the boundaries of the United States (National Geographic).

There are different types of eruptive events. We can distinguish between primary and secondary events.

Volcanoes can have many different appearances. The shape of a volcano provides clues to the type and size of eruption that occurred. Eruption types and sizes depend on what the magma is made up of. Three common volcano forms are:

Shield volcano: have a broad, flattened dome-like shape created by layers of hot and runny lava flowing over its surface and cooling.

Composite volcano : also known as stratovolcanoes, they are formed from explosive eruptions. These eruptions create steep sided cones.

Caldera volcano: these volcanoes erupt so explosively that little material builds up near the vent. Eruptions partly or entirely empty the underlying magma chamber which leaves the region around the vent unsupported, causing it to sink or collapse under its own weight. The resulting basin-shaped depression is roughly circular and is usually several kilometres or more in diameter (Australian Government).

Related content

News

A team of scientists, led by the University of Bristol’s School of Earth Sciences, has used Sentinel-1 satellite imagery to analyze the ground deformation of the Agung volcano in Bali, Indonesia, and explain why it erupted in November 2017 after 50 years of dormancy.

The previous eruption of Agung in 1963 killed nearly 2,000 people and was followed by a small eruption of its neighbouring volcano, Batur. Because this past event was among the deadliest volcanic eruptions of the 20th century, the scientific community deployed a great effort into the monitoring and understanding of the re-awakening of Agung.

Two months before the eruption, a sudden increase in the number of small earthquakes occurred around the volcano. The researchers realized satellite... read more

UN-SPIDER and the National Secretariat for Science and Technology of Guatemala (SENACYT) join forces to conduct a seminar on the use of science, technology and innovation in disaster risk reduction and response efforts. The seminar entitled "Science and Technology: Applications for... read more

Data Source

The Global Volcanism Program database currently contains 1432 volcanoes with eruptions during the Holocene period (approximately the last 10,000 years). Primary names are sorted below in alphabetical order. Please use the volcano search page to find other names and create a list with synonyms and subfeatures.

Movebank is a free, online database of animal tracking data hosted by the Max Planck Institute for Ornithology. The institute help animal tracking researchers to manage, share, protect, analyze, and archive their data. The animal tracking data in Movebank belongs to researchers all over the world who choose whether and how to share their data with the public. Curretnr esearch is being done on animal derived early warning systems for earthquakes, volcanoes and landslides.

ESA's Earth Observation Thematic Exploitation Platform (TEP) is a browser for satellite imagery and specific products on an environmental topic. The TEP platforms are divided into 7 categories: Coastal; Forstry; Geohazards; Hydrology; Polar; Urban; and Food Security. Each platform is a collaborative, virtual work environment providing access to EO data and the tools, processors and Information and Communication Technology resources required to work with them. TEP aims to bridge the gap between the users and the data and tools.